WFC 111 Avian Sensory systems

vision

most important sense in birds; largest eye:body size ration; essential for safe flight (movement in 3D)

lens

focuses light to keep things sharp

eyes

cornea, pupil, iris, lens, retina, optic nerve, optic lobe brain

bird eye differences

larger (but reduced mobility), scleral ring, 2 lens focusing system (cornea + lens), pecten, multiple fovea

pecten

organ that provides nutritional support to retina

bird optical lobe

extremely large in order to process a lot of complex info quickly

eye shape

different bone structure (scleral ring) and muscles (change shape of lens and cornea to focus light); for situations like underwater, close up, or far away

scleral ring

ring of bony ossicles around eye, protects eyeball, holds shape during fast movement (flying), for muscle attachment

flexible lens

softer, allows for faster more precise focus

Retina

higher density of photoreceptors, 4 cones (RBG + UV)

ultraviolet vision 

bc tetrachromatic, helpful for foraging, egg recognition, and social behaviors, (not in paleognaths)

fovea

birds have 2 (central and temporal) (can focus in multiple laces at once); divots in retina, focal points for vision,

nictitating membranes

third clear eyelid that acts as protective google, good for highspeed/underwater

sound

birds 2nd best sense

avian ear

simple; single bone (columella) from eardrum to cochlea (remember some moved to the jaw); reduced range of hearing (lower frequencies)

facial disc

like a satellite dish to direct sound to ear openings

ear openings

asymmetrical to give depth perception; right (above); left (below)

predator calls

higher pitch in order to alert each other while predators can't hear it; birds can also communicate level of threat 

echolocation

in oilbirds and swiftlets; rudimentary but allows for night flight

avian olfaction

relatively poor sense, widely variable

ethyl mercaptan

compound we add to gas that vulture also smell

Procellariiformes

tube-nosed seabirds; have great sense of smell; most developed olfactory bulb in birds; detects dimethyl sulfide (DMS); chicks learn scent from parents

herbst corpuscle

tactile sensory pits on bills

homing pigeons

use magnetism to navigate home

magnetic reception

via iron deposits and magnetoreceptors near end of bill (crytochrome cells)